package com.ht.baselibs.ui.widget;

import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.animation.Interpolator;

import java.lang.ref.WeakReference;
import java.lang.reflect.Field;


/**
 * AutoScrollViewPager 自动滚动的ViewPager 搭配着 Pageindicator 使用
 */
public class AutoScrollViewPager extends ViewPager {

        public static final int        DEFAULT_INTERVAL            = 1500;

        public static final int        LEFT                        = 0;
        public static final int        RIGHT                       = 1;

        /** do nothing when sliding at the last or first item **/
        public static final int        SLIDE_BORDER_MODE_NONE      = 0;
        /** cycle when sliding at the last or first item **/
        public static final int        SLIDE_BORDER_MODE_CYCLE     = 1;
        /** deliver event to parent when sliding at the last or first item **/
        public static final int        SLIDE_BORDER_MODE_TO_PARENT = 2;

        /** auto scroll time in milliseconds, default is {@link #DEFAULT_INTERVAL} **/
        private long                   interval                    = DEFAULT_INTERVAL;
        /** auto scroll direction, default is {@link #RIGHT} **/
        private int                    direction                   = RIGHT;
        /** whether automatic cycle when auto scroll reaching the last or first item, default is true **/
        private boolean                isCycle                     = true;
        /** whether stop auto scroll when touching, default is true **/
        private boolean                stopScrollWhenTouch         = true;
        /** how to process when sliding at the last or first item, default is {@link #SLIDE_BORDER_MODE_NONE} **/
        private int                    slideBorderMode             = SLIDE_BORDER_MODE_NONE;
        /** whether animating when auto scroll at the last or first item **/
        private boolean                isBorderAnimation           = true;
        /** scroll factor for auto scroll animation, default is 1.0 **/
        private double                 autoScrollFactor            = 1.0;
        /** scroll factor for swipe scroll animation, default is 1.0 **/
        private double                 swipeScrollFactor           = 1.0;

        private Handler                handler;
        private boolean                isAutoScroll                = false;
        private boolean                isStopByTouch               = false;
        private float                  touchX                      = 0f, downX = 0f;
        private CustomDurationScroller scroller                    = null;

        public static final int        SCROLL_WHAT                 = 0;

        public AutoScrollViewPager(Context paramContext) {
                super(paramContext);
                init();
        }

        public AutoScrollViewPager(Context paramContext, AttributeSet paramAttributeSet) {
                super(paramContext, paramAttributeSet);
                init();
        }

        private void init() {
                handler = new MyHandler(this);
                setViewPagerScroller();
        }

        /**
         * start auto scroll, first scroll delay time is {@link #getInterval()}
         */
        public void startAutoScroll() {
                isAutoScroll = true;
                sendScrollMessage((long)(interval + scroller.getDuration() / autoScrollFactor * swipeScrollFactor));
        }

        /**
         * start auto scroll
         *
         * @param delayTimeInMills first scroll delay time
         */
        public void startAutoScroll(int delayTimeInMills) {
                isAutoScroll = true;
                sendScrollMessage(delayTimeInMills);
        }

        /**
         * stop auto scroll
         */
        public void stopAutoScroll() {
                isAutoScroll = false;
                handler.removeMessages(SCROLL_WHAT);
        }

        /**
         * set the factor by which the duration of sliding animation will change while swiping
         */
        public void setSwipeScrollDurationFactor(double scrollFactor) {
                swipeScrollFactor = scrollFactor;
        }

        /**
         * set the factor by which the duration of sliding animation will change while auto scrolling
         */
        public void setAutoScrollDurationFactor(double scrollFactor) {
                autoScrollFactor = scrollFactor;
        }

        private void sendScrollMessage(long delayTimeInMills) {
                /** remove messages before, keeps one message is running at most **/
                handler.removeMessages(SCROLL_WHAT);
                handler.sendEmptyMessageDelayed(SCROLL_WHAT, delayTimeInMills);
        }

        /**
         * set ViewPager scroller to change animation duration when sliding
         */
        private void setViewPagerScroller() {
                try {
                        Field scrollerField = ViewPager.class.getDeclaredField("mScroller");
                        scrollerField.setAccessible(true);
                        Field interpolatorField = ViewPager.class.getDeclaredField("sInterpolator");
                        interpolatorField.setAccessible(true);

                        scroller = new CustomDurationScroller(getContext(), (Interpolator)interpolatorField.get(null));
                        scrollerField.set(this, scroller);
                } catch (Exception e) {
                        e.printStackTrace();
                }
        }

        /**
         * scroll only once
         */
        public void scrollOnce() {
                PagerAdapter adapter = getAdapter();
                int currentItem = getCurrentItem();
                int totalCount;
                if (adapter == null || (totalCount = adapter.getCount()) <= 1) {
                        return;
                }

                int nextItem = (direction == LEFT) ? --currentItem : ++currentItem;
                if (nextItem < 0) {
                        if (isCycle) {
                                setCurrentItem(totalCount - 1, isBorderAnimation);
                        }
                } else if (nextItem == totalCount) {
                        if (isCycle) {
                                setCurrentItem(0, isBorderAnimation);
                        }
                } else {
                        setCurrentItem(nextItem, true);
                }
        }

        /**
         * <ul>
         * if stopScrollWhenTouch is true
         * <li>if event is down, stop auto scroll.</li>
         * <li>if event is up, start auto scroll again.</li>
         * </ul>
         */
        @Override
        public boolean dispatchTouchEvent(MotionEvent ev) {
                int action = MotionEventCompat.getActionMasked(ev);

                if (stopScrollWhenTouch) {
                        if ((action == MotionEvent.ACTION_DOWN) && isAutoScroll) {
                                isStopByTouch = true;
                                stopAutoScroll();
                        } else if (ev.getAction() == MotionEvent.ACTION_UP && isStopByTouch) {
                                startAutoScroll();
                        }
                }

//                if (slideBorderMode == SLIDE_BORDER_MODE_TO_PARENT || slideBorderMode == SLIDE_BORDER_MODE_CYCLE) {
//                        touchX = ev.getX();
//                        if (ev.getAction() == MotionEvent.ACTION_DOWN) {
//                                downX = touchX;
//                        }
//                        int currentItem = getCurrentItem();
//                        PagerAdapter adapter = getAdapter();
//                        int pageCount = adapter == null ? 0 : adapter.getCount();
//                        /**
//                         * current index is first one and slide to right or current index is last one and slide to left.<br/>
//                         * if slide border mode is to parent, then requestDisallowInterceptTouchEvent false.<br/>
//                         * else scroll to last one when current item is first one, scroll to first one when current item is last
//                         * one.
//                         */
//                        if ((currentItem == 0 && downX <= touchX) || (currentItem == pageCount - 1 && downX >= touchX)) {
//                                if (slideBorderMode == SLIDE_BORDER_MODE_TO_PARENT) {
//                                        getParent().requestDisallowInterceptTouchEvent(false);
//                                } else {
//                                        if (pageCount > 1) {
//                                                setCurrentItem(pageCount - currentItem - 1, isBorderAnimation);
//                                        }
//                                        getParent().requestDisallowInterceptTouchEvent(true);
//                                }
//                                return super.dispatchTouchEvent(ev);
//                        }
//                }
//                getParent().requestDisallowInterceptTouchEvent(true);

                return super.dispatchTouchEvent(ev);
        }

        private static class MyHandler extends Handler {

                private final WeakReference<AutoScrollViewPager> autoScrollViewPager;

                public MyHandler(AutoScrollViewPager autoScrollViewPager) {
                        this.autoScrollViewPager = new WeakReference<AutoScrollViewPager>(autoScrollViewPager);
                }

                @Override
                public void handleMessage(Message msg) {
                        super.handleMessage(msg);

                        switch (msg.what) {
                                case SCROLL_WHAT:
                                        AutoScrollViewPager pager = this.autoScrollViewPager.get();
                                        if (pager != null) {
                                                pager.scroller.setScrollDurationFactor(pager.autoScrollFactor);
                                                pager.scrollOnce();
                                                pager.scroller.setScrollDurationFactor(pager.swipeScrollFactor);
                                                pager.sendScrollMessage(pager.interval + pager.scroller.getDuration());
                                        }
                                default:
                                        break;
                        }
                }
        }

        /**
         * get auto scroll time in milliseconds, default is {@link #DEFAULT_INTERVAL}
         *
         * @return the interval
         */
        public long getInterval() {
                return interval;
        }

        /**
         * set auto scroll time in milliseconds, default is {@link #DEFAULT_INTERVAL}
         *
         * @param interval the interval to set
         */
        public void setInterval(long interval) {
                this.interval = interval;
        }

        /**
         * get auto scroll direction
         *
         * @return {@link #LEFT} or {@link #RIGHT}, default is {@link #RIGHT}
         */
        public int getDirection() {
                return (direction == LEFT) ? LEFT : RIGHT;
        }

        /**
         * set auto scroll direction
         *
         * @param direction {@link #LEFT} or {@link #RIGHT}, default is {@link #RIGHT}
         */
        public void setDirection(int direction) {
                this.direction = direction;
        }

        /**
         * whether automatic cycle when auto scroll reaching the last or first item, default is true
         *
         * @return the isCycle
         */
        public boolean isCycle() {
                return isCycle;
        }

        /**
         * set whether automatic cycle when auto scroll reaching the last or first item, default is true
         *
         * @param isCycle the isCycle to set
         */
        public void setCycle(boolean isCycle) {
                this.isCycle = isCycle;
        }

        /**
         * whether stop auto scroll when touching, default is true
         *
         * @return the stopScrollWhenTouch
         */
        public boolean isStopScrollWhenTouch() {
                return stopScrollWhenTouch;
        }

        /**
         * set whether stop auto scroll when touching, default is true
         *
         * @param stopScrollWhenTouch
         */
        public void setStopScrollWhenTouch(boolean stopScrollWhenTouch) {
                this.stopScrollWhenTouch = stopScrollWhenTouch;
        }

        /**
         * get how to process when sliding at the last or first item
         *
         * @return the slideBorderMode {@link #SLIDE_BORDER_MODE_NONE}, {@link #SLIDE_BORDER_MODE_TO_PARENT},
         *         {@link #SLIDE_BORDER_MODE_CYCLE}, default is {@link #SLIDE_BORDER_MODE_NONE}
         */
        public int getSlideBorderMode() {
                return slideBorderMode;
        }

        /**
         * set how to process when sliding at the last or first item
         *
         * @param slideBorderMode {@link #SLIDE_BORDER_MODE_NONE}, {@link #SLIDE_BORDER_MODE_TO_PARENT},
         *        {@link #SLIDE_BORDER_MODE_CYCLE}, default is {@link #SLIDE_BORDER_MODE_NONE}
         */
        public void setSlideBorderMode(int slideBorderMode) {
                this.slideBorderMode = slideBorderMode;
        }

        /**
         * whether animating when auto scroll at the last or first item, default is true
         *
         * @return
         */
        public boolean isBorderAnimation() {
                return isBorderAnimation;
        }

        /**
         * set whether animating when auto scroll at the last or first item, default is true
         *
         * @param isBorderAnimation
         */
        public void setBorderAnimation(boolean isBorderAnimation) {
                this.isBorderAnimation = isBorderAnimation;
        }
}
